This invention relates to an automatic transmission for vehicle and more particularly to a fluid pressure control system for governing a planetary or epicyclic gear trains employed in the transmission.
As used herein, the term "low position" refers to a high ratio differential achieved by the planetary gear trains adapted for the slowest travelling speed of the vehicle.
The term "second position" refers to a middle level ratio differential achieved by the gear trains adapted for the middle level vehicle travelling speed.
The term "top position" refers to a position in which the entire mechanism of the gear trains is locked together as a unit and is rotated in integral with an input shaft for achieving a higher travelling speed of the vehicle.
Known automatic transmissions adapted for vehicles are not ordinarily able to completely interrupt torque transmission although acceleration pedal is completely released by the vehicle driver in case where the vehicle stops travelling as in conformity with the traffic signal on the roads.